A feed forward neural network is applied to the analysis of K-shell X-ray line spectra from a laser produced plasma, and to the accurate determination of the plasma parameters. After training on error backpropagation algorithm, the network can effectively produce the electron temperatures and the electron densities. The use of this method for X-ray is illustrated. Spectroscopy of a high density and high temperature Mg plasma is illustrated. The both parameters are produced, and agree well with the results from conventional method.